Summary: Dipole­dipole interactions among CH3Cl molecules on Ru,,001...: Correlation
between work function change and thermal desorption studies
T. Livneh,a)
Y. Lilach, and M. Asscher
Department of Physical Chemistry and the Farkas Center for Light Induced Processes,
The Hebrew University, Jerusalem 91904, Israel
Received 26 March 1999; accepted 21 September 1999
Work function change measurements combined with temperature programmed desorption
TPD were employed to study layer growth mechanism and the CH3Cl dipole­dipole interactions
on Ru 001 , over the temperature range of 97 K­230 K. The activation energy for desorption (Ea)
and the molecular dipole moment both decrease from 55.9 kJ/mol and 2.44 D, at the zero
coverage limit, to 38.6 kJ/mol and 1.27 D, at one monolayer. This coverage dependence originates
from strong dipolar lateral repulsion among neighbor CH3Cl molecules. Using a model introduced
by Maschhoff and Cowin MC J. Chem. Phys. 101, 8138 1994 , the isolated adsorbed molecule's
dipole moment, 0 2.35 D and polarizability (8.1 10 24
cm3
), were extracted from TPD data.
These values agree very well with 0 2.12 D and (9.2 10 24
cm3
) obtained from work function

Source: Asscher, Micha - Institute of Chemistry, Hebrew University of Jerusalem

Collections: Chemistry